Process for sweetening sour hydrocarbon oil



Patented Apr. 6, 1943 PROCESS FOR SWEETENIN G SOUR HYDROCARBON 01L Walter A. Schulze and Al 0kla., assignors to Phi bert E. Buell, Bartlesville. llips Petroleum Company,

a corporation of Delaware N 0 Drawing. Continu ation of application Serial No. 166,022, September 27, 1937. This application May 27, 1940, Serial No. 337,548

10 Claims.

This invention relates to the refining of hydro carbon products and particularly to the refining 01' petroleumproducts containing malodorous sulfur compounds of the mercaptan type. More speg cifically, it relates to the preparation and use of moist solid reagents comprising copper solutions adsorbed on carriers for sweetening "sour p9- troleum hydrocarbon products. The invention is of special value and application for the treatment of light petroleum distillates such as natural gasoline, refinery straight run and petroleum solvent naphthas, liquefied petroleum gases and the like.

This application is a continuation of application Serial No. 166,022, filed September 27, 1937.

Such unrefined petroleum products contain mercaptans, commonly called sour elements. which give the oil undesirable odor, and corrosive and unstable. Until recently these compounds have been customarily removed, or altered, by the so-called doctor process, a laborious, cumbersome and very uneconomical-chemical treatment with alkaline plumbite and sulphur. In some instances, e. g.. natural gasoline, the sweetening action has been accomplished through the use of alkaline hypochlorite solutions, but this method, too, has not proved cases due to the introduction into the oil of undesirable constituents as bad as those originally present. Recently, however, sweetening of certain petroleum products has been accomplished with much improved results through the use of moist solid copper reagents as described in a copending application by Buell. Serial No. 121,908. filed January 22. 1937 now U. S. Patent 2,094,485 granted September 28. 1937.

One of the principal objects of the present in vcntion is to provide moist solid copper reagents of the proper composition for the treatment of the various types of petroleum products.

Another object of the invention is to extend the scope of the solid copper reag nt process so that products which could not heretofore be treated satisfactorily with solid copper reagents may now be treated with excellent results.

Still another object of the invention is to provide solid copper sweetening reagents which will rapidly and efiectively convert mercaptans to disulfides without. appreciable color change of the cracked gasolines.

satisfactory in most oil and without decreasing the stability of said oil. 1

Still another object of the invention is to set forth the proper fiow rates forthe treatment of the various petroleum oils over the herein described copper reagents, such flow rates being critical withrespect to the quality of the sweetened petroleum product as well as to the life of the reagent.

render it.

- contents, and water.

' sorbed treating Another object of the invention is to set forth the proper temperature for treatment of the vari ous petroleum oils with the herein described copper reagents, such temperature being critical with respect to the quality of the sweetened petroleum oils;

We have discovered that; the composition of the copper reagent plays a most important role in the production of sweetened oils of good color and good stability. As described in the Buell application, Serial No. 121,908, (Patent 2,094,485) moisture is an essential requirement. In addition to this requirement, we have now discovered that there must be a definite relationship between the amounts of. adsorbent These so-called solid copper reagents are in fact adsorbent carriers impregnated with aqueous solutions comprising the two components, cupric copper and chloride, which are necessary for the sweetening the surface of the adsorbent by adsorptive forces and is retained in place so long as the quantity of the solution doesnot exceed this capacity. Thus,

for any given adsorbent there is #a maximum amount of treating solution which can be held by a unit portion of the adsorbent. Also, the various it is about 20 cc. per 100 grams.

We have discovered now that the concentrations of cupric copper and'of chloride in this adsolution are extremely critical and must be maintained within certain limitsin order to obtain sweetened oils which are of good carrier, copper and chloride reaction. The Solution is held onto chloride must be kept within the limits prescribed below.

In the preparation of our solid copper reagents we have found that the total weight of copper sulfate and sodium chloride to that of water should be within the limits of about 0.20 to 0.85. The composition of several typical reagents listed below illustrates this point.

The copper sulfate and sodium chloride need not be employed in the ratio of one moi of the former to two moles of the latter but, preferably, less than one moi of cupri copper to more than two moles of chloride. The ratio of chloride to water should be held within the limits of 0.05 to 0.35 as shown by several typical reagents in Table II.

Table II Per cent by weight Ratio:

Chloride Water Reagent No. l-.- 3. 52 26. 0 0. l4 Reagent No. 2 2.13 24. 5 Q. 09 Reagent No. 6 3. 83" 17.8 0. 22 Reagent No. 7 4.10 13.0 0.31 Reagent No. 8 1. 47 20. 2 0.06

The treating solution containing the requisite cupric copper and chloride may be prepared, of course, from any soluble salts producing the cupric copper and chloride ions in solution.

If the copper solution on the adsorbent is too concentrated with respect to chloride, 1. e., if it has a chloride to water ratio greater than 0.35, the reagent when placed in service for sweetening oils such as vapor recovery gasolines, kerosenes and the like, will cause a decrease in Saybolt color and in gum stability of such cils. With very high chloride to water ratios, hydrochloric acid will be given off the reagent and will contaminate the oil; simultaneously the treated oils will contain soluble copper compounds which cause rapid deterioration of the product and oftentimes it may even react sour to the doctor test.

On the other hand, if the copper solution on the adsorbent is too dilute with respect to chlo ride, i. e., if it has a chloride to water ratio less 7 than 0.05, the sweetening reaction will be too slow and hence there will be a rapid migration of the copper compounds through the filter bed in the direction of flow of the oil. This migration of the copper is equivalent to spending of the reagent and hence cannot be permitted. Thus, it is imperative that the chloride to water ratio be maintained, as we have discovered, within the limits of 0.05 to 0.35.

The following examples are given as illustrative of the results secured with solid copper reagents when treating several typical oils.

E ram pZe I A sour vapor recovery gasoline from Mid-Continent crude was treated over a copper reagent containing 2.13 per cent chloride and 22.0 per treated product was completely sweetened, contained no trace of copper, was +30 Saybolt color, and showed no color or appreciable gum formation during two months storage. More than 1000 volumes of the gasoline per volume or reagent were treated without any detectabl migration of copper in the reagent bed.

On the other hand, when some of the same vapor recovery gasoline was treated with a copper reagent having a chloride to water ratio of approximately 040, the treated product was only +16 color and showed appreciable gum formation during a short storage period. Similarly, when a copper reagent having a chloride to water ratio of approximately 0.03, the treated product contained copper and showed rapid deterioration in color and gum stability during a few days storage. At the same time it was noted that much of the copper migrated through the bed and was carried out with' the gasoline.

Example II A sour kerosene of 43.6 A. P. I. gravity and a mercaptan sulfur content of 0.024 per cent was treated with a copper reagent comprising by weight 087 hr cent'cupric copper, 2.13 per cent chloride, 1.37 percent sodium, 1.31 per cent sulfate, 24.5 per cent water and 69.82 per cent 16 to 30 mesh fullers earth. This reagent has a chloride to water ratio of 0.09. At a treating rate of 3 volumes per hour per volume of reagent the product was 28 to 29 color, was entirely free of copper and was stable in storage. A reagent with a. chloride to water ratio of 0.37 gave an extremely yellow product of very undesirable characteris-' tics. Also, a reagent with a chloride to water ratio of 0.04 gave both an unsatisfactory product and unsatisfactory service.

In the conversion of mercaptans to disulfides by means of oxygen from the air and these catalytic solid copper reagents, water is formed in an amount proportional to the percent of mercaptan sulfur in the sour oil. This water of reaction, if in excess of that soluble in the oil, will be left in the reagent and will dilute the copper solution adsorbed thereon. Moreover, since most of the sweetening is done in the initial portion of the reagent bed, most of the dilution will occur first in this section instead of being uniformly distributed throughout the filter bed. If an oil is very high in mercaptan content, considerable dilution of the solution on the reagent will take place and periodically the solution will need concentration. On the other hand, if the oil is very low in mercaptan content, it may actually extract water from the copper solution on the adsorbent and tend to make the solution too concentrated. When a reagent is used in such service, it is frequently diluted so as to maintain the chloride to water ratio within the proper limits.

We have found too that the chloride to water ratio may be more readily maintained and that less migration of the copper takes place through the filter bed when salts which readily form hydrates are added to the treating solutions'along with the cupric copper and chloride. Examples of such substances are sodium sulfate, magnesium sulfate, calcium chloride and the like.

treatment of these stocks.

We have discovered too inasmuch as the'varions oils show varying degrees of stability that much improved results may be obtained during that for extremely unstable stocks. best results.

may be secured through the use of reagents havscribed limits, i. e., 0.35 to 0.25. For exampl :in the treatment Table III Ratio: Flow rate. Temperchloride volumes ature All of the fractions were completely sweet, did not contain any copper and were quite stable in stor- Nevertheless, it is quite obvious that the most desirable results were secured from the reagent with the 0.09 chloride to water ratio. Likeposltion unchanged the color loss decreased with an increased flow rate. When treating with the reagents having a low chloride to water concenof heavy oils such as kerosenes or heating oils. Also, the oils may be contaminated with copper compounds.

These solid copper sweetening reagents during use may be maintained. within the proper limits of chloride to water either, in situor by-removing fromthe towers and readjusting in the proper;

direction.

Weclaim: g a 1. A process, for sweetening sour hydrocarbon oils relatively unstable with between 0.05 a d 015,; 13 and 26 per cent water.

3. A process for sweetening sour hydrocarbon oils rela 0.20 and 0.85, and containing between 13 and 26 per cent water.

4. In a process for sweetening sour hydrocarbon oils relatively unstable with respect to color per cent water.

A process for sweetening sour hydrocarbon oils relatively unstable with respect to color'anci slum suliate. and calcium chloride.

for sweetening a sour hydrocar such an oil in ing reagent comprising a solid adsorbent carrier impregnated with an aqueous solution containing between 13 and 26 per cent water and containing cupric ions, a soluble chloride, and an amount of an inorganic salt of a metal of non-variable valence, capable oi forming a crystalline hydrate in which is incorporated water of crystallization and selected from the group consisting of sodium sulfate. magnesium sulfate and calcium'chloride, suiilcient to effect a stabilization of the water content of said solid reagent.

9. In a process for sweetening a sour hydrocarbon traction by passing said i'raction over a solid copper sweetening reagent in admixture with suiiicient free oxygen to maintain the activity of said reagent comprising an adsorbent carrier impregnated with an aqueous soluimprovement which comprises maintaining the COmPOSitiOD-sOI said reagent such as to comprise between about 60 and 85 per cent by weight of granular adsorbent material, a weight ratio oi chloride to water between about 0.05 to 0.35, and a molar ratio of copper to chloride of not more than 0.5.

10. An improved process for sweetening a hydrocarbon oil which is both sour and relatively unstable with respect to color and gum formation, which comprises treating said oil'in the presence of free oxygen and a. solid copper sweetening solid granular adsorbent material on which is adsorbed an aqueous solution containing cupric ions and chloride ions, and maintaining the composition of said solid reagent such as to comprise between about 60 and 85 per cent by weight of granular adsorbent material, a weight ratio of chloride to water between about 0.05 and,0.25, and a molar ratio or copper to chloride of not more than 0.

WALTER A. SCHULZE. ALBERT E. BUELL. 

